EVIDENCE FOR A FUNCTIONAL INTERACTION BETWEEN THE BETA-CHAIN OF MAJORHISTOCOMPATIBILITY COMPLEX CLASS-II AND THE T-CELL RECEPTOR-ALPHA CHAIN DURING RECOGNITION OF A BACTERIAL SUPERANTIGEN

Several studies have suggested that there is a direct interaction betw een the T cell receptor (TCR) and the major histocompatibility complex (MHC) molecule during T cell recognition of superantigen. To further investigate this possibility, we have analyzed T cell recognition of a bacterial superantigen, Staphylococcal enterotoxin B (SEB), presented by a series of mutant murine I-E(k) molecules in which residues of ei ther the alpha or beta chain predicted to interact with the TCR have b een substituted. Individual T cell hybridomas gave distinct patterns o f responsiveness to SEB presented by the I-E beta(k) mutants that coul d not be attributed to differences in the binding of SEB to the mutant s. This effect appeared to be dependent on the TCR-alpha chain because some of these hybridomas expressed identical TCR transgenic beta chai ns. In contrast, none of the hybridomas gave distinct patterns of resp onsiveness to SEB presented by the I-E alpha(k) mutants. Taken togethe r, these observations support the idea that there is a functional inte raction between the alpha chain of the TCR and the beta chain of the M HC class II molecule. The data also support the idea that this interac tion might enhance superantigen recognition in some cases.